I must admit I've grown bored with FPS games--and had long ago given up on Prey--but this has me intrigued:

All the portals, wall-walking paths, and orientation changes that put doors on walls and ceilings mean that losing sight, even for only a moment, can present the opportunity to slip away.

Imagine that you are chasing someone down a wall-walk path. It's hard to keep up with all the twisting and turning as you race after them, guns blazing. Suddenly, you come around the corner into a new room, and they're gone. Before you lies a portal, a couple of doors, and a gravity switch. Which way did they go? What's worse is that your quarry has probably setup camp just through whichever way they did go, with a bead drawn at about head-height ready to ambush you should you actually choose to go the same direction they did.